Skiff Sokolov

Evaluation of a photon-counting mammography system

The most natural way of digital X-ray imaging is photon counting as the photon flux in itself is digital. In photon counting, the information in the X-ray flux is used more efficiently as the information carrying low-energy photons are given the same weight as higher energy photons carrying less image information. This is in contrast to all existing X-ray instruments, which are energy-integrating systems where the highest energy photons are given the highest weight. A novel technique for high resolution digital X-ray imaging, using gaseous avalanche detectors for photon counting with high signal-to-noise ratios for single X-ray photons, has been developed. The performance of this detector has been studied and compared to analogue film-screen system by imaging phantoms. Our results show that this technology can improve image quality while decreasing the glandular dose to the patient.

Dose reduction in mammography with photon counting imaging

The purpose of this study was to investigate if the glandular dose to the breast in mammography can significantly be reduced without compromising image quality, when using photon counting technology, in a multi-slit scanning photon counting detector, compared to a conventional film mammography system and commercial available digital mammography systems with TFT-array detectors. A CDMAM phantom study, with two different thicknesses of additional PMMA absorber, 4 cm and 7 cm respectively, has shown that multi-slit scanning photon counting detector technology can reduce the dose, without reducing the image quality. This comparison was made to two commercial available digital mammography systems Senographe 2000D (from GEMS) and Selenia (from Lorad). The results show that dose can be reduced with 63% to 77%, depending on object thickness, when using XCT for mammography. This dose reduction has also been verified clinically through a small pilot study with patients and specimen, where the comparison was made between XCT and film.

Dose reduction using photon-counting x-ray imaging

Radiation dose to the patient, contrast and position resolution are important quality factors in medical X-ray imaging. A novel technique for digital X-ray imaging has been developed, using photon counting with high signal-to-noise ratios for single X-ray photons. The novel technique allows a significant dose reduction over screen-film systems, as well as a high contrast and good position resolution. The novel technique is based on photon counting gaseous detectors. A high signal-to-noise ratio for single X-ray photons allows virtually noise-free counting of photons. Low noise together with a high contrast in the image allows a significant dose reduction compared to film-based systems. The new technique makes photon counting X-ray imaging possible, only limited by quantum fluctuations.

Clinical evaluation of a photon-counting tomosynthesis mammography system

Digital breast tomosynthesis promises solutions to many of the problems currently associated with projection mammography, including elimination of artifactual densities from the superposition of normal tissues and increasing the conspicuity of true lesions that would otherwise be masked by superimposed normal tissue. We have investigated the performance of a novel tomosynthesis system in a clinical setup. The novel system uses 48 photon counting, orientation sensitive, linear detectors which are precisely aligned with the focal spot of the x-ray source. The x-ray source and the digital detectors are scanned in a continuous motion across the patient; each linear detector collecting an image at a distinct angle. The results from an assessment of image quality and the initial clinical trial of this device are presented. Initial results provide anecdotal evidence supporting the superiority of tomosynthesis over projection mammography.